Lamp Watts vs System Watts – LED Lighting Power consumption and Costs

When considering purchasing a new luminaire, understanding its energy consumption and associated costs is crucial. Many buyers assume that the wattage indicated on the lamp is the total energy consumption, but this is not always the case. The actual power usage, known as system watts, can be significantly higher, impacting your energy costs over time. This guide will explain the difference between lamp watts vs system watts, and why knowing this distinction is essential for making informed decisions.

Considering Buying New Lighting? Understand Its Power Consumption and Costs

Considering buying a new luminaire and curious about its energy consumption and the associated cost? Buyer beware! The watts used have a basis in the lamp or lamps, but it is not based exclusively on the wattage of the lamp.

Why Does It Matter?

Energy is expensive. You may think the luminaire you purchased for your business or otherwise uses 400 watts but the real usage may be 458 watts. Based on electricity priced at $.15/kWh and a luminaire being used 12 hours a day 5 days a week, the difference of 58 watts would cost an extra $27.26 per year. Most lighting projects use many fixtures so the unexpected cost could be significant.

What is Lamp Watts?

Lamp watts are the watts that a lamp is rated for. For instance, a 400-watt metal halide lamp is rated for 400 watts. A 1000-watt high-pressure sodium lamp is rated for 1000 watts. One might expect that to be the end of the story, but it is not.

What is System Watts?

Most lamps, except for basic incandescent lamps, which run on line voltage, use a ballast. The ballast takes the voltage provided and changes it to the correct format to light the lamp and keep it lit. The ballast requires watts too. System watts are the total watts the lamp and the ballast use together. The system watts for a 400-watt metal halide is about 458 watts depending on the ballast.  When you purchase a new luminaire or compare one lighting technology to another, be sure to ask for the system watts. That way you know which system is more energy efficient and what the system will cost to operate.

Older Lighting Technologies: Metal Halide and High-Pressure Sodium

Understanding the Difference Between Lamp Wattage and System Wattage for LED Lights

Are you considering purchasing a new luminaire and curious about its energy consumption and the associated costs? Buyer beware! The wattage of a luminaire isn’t solely based on the lamp’s wattage.

Why Does It Matter?

Energy costs can add up. You might think the luminaire you purchased uses a certain wattage, but the actual usage could be higher. For instance, if you think your luminaire uses 100 watts but it actually uses 115 watts, the difference in energy costs can be significant over time. Based on an electricity price of $0.15 per kWh and using the luminaire for 12 hours a day, 5 days a week, the additional 15 watts could cost you an extra $14 per year per luminaire. If your business uses many fixtures, these unexpected costs can quickly add up.

What Are Lamp Watts?

Lamp watts refer to the wattage rating of the lamp itself. For example, an LED lamp rated at 100 watts is expected to use 100 watts. However, this is not the whole story.

What Are System Watts?

System watts are the total watts consumed by the lamp and any additional components, such as drivers or ballasts. These components convert the supplied voltage to the correct format for the lamp and maintain its operation. For LED lights, the driver also consumes power, which means the system watts will be slightly higher than the lamp watts. For example, an LED lamp rated at 100 watts might have system watts of around 115 watts.

When purchasing a new luminaire or comparing different lighting technologies, always ask for the system watts. This will give you a better understanding of the energy efficiency and operating costs of the system.

Example System Wattage Comparisons

To calculate the system watts, you need to add the wattage consumed by the lamp to the wattage consumed by any additional components, such as drivers or ballasts. The general formula is:

System Watts=Lamp Watts+Driver/ Ballast Watts

For LED systems, this can be broken down into:

System Watts = Lamp Watts × (1+Driver Efficiency Loss)

Where:

• Lamp Watts is the wattage rating of the lamp.
• Driver Efficiency Loss is the percentage of additional watts consumed by the driver. This is usually provided as a percentage (e.g., if the driver efficiency is 90%, the driver efficiency loss is 10% or 0.10).

For example, if you have a 100-watt LED lamp and the driver efficiency is 90% (which means the driver efficiency loss is 10% or 0.10):

System Watts = 100 watts × (1+0.10) = 100 watts × 1.10 = 110 watts

This formula helps you determine the total power consumption of the luminaire, ensuring more accurate energy consumption calculations.

Understanding the difference between lamp watts and system watts ensures you make informed decisions about your lighting solutions, leading to more accurate energy consumption forecasts and cost savings.

For more information about the difference between lamp watts and system watts, contact an Access Fixtures lighting specialist.

Conclusion

Understanding the difference between lamp watts and system watts is essential for making informed decisions about your lighting solutions. Accurate knowledge of energy consumption helps in forecasting costs and identifying the most energy-efficient systems. By considering both lamp watts and system watts, you can ensure that your investments in lighting technology are cost-effective and sustainable in the long run. For more detailed information and guidance, consult an Access Fixtures lighting specialist.

Lamp Watts and System Watts Frequently Asked Questions (FAQs)

You have Lamp Watts and System Watts Lighting questions. We have answers. If you have a question that isn’t answered below, contact an Access Fixtures lighting specialist at (800) 468-9925 or click here to visit our customer service page.

What are lamp watts?

• • Lamp watts refer to the wattage rating of the lamp itself, indicating the power it consumes under standard conditions.

What are system watts?

• • System watts are the total watts consumed by the lamp and any additional components, such as drivers or ballasts, required to operate the lamp.

Why are system watts higher than lamp watts?

• • Additional components like ballasts or drivers consume extra power to convert the supplied voltage to the correct format for the lamp, increasing the total wattage used.

How do I calculate system watts for LED lights?

• • System watts can be calculated using the formula: $\text{System Watts}=\text{Lamp Watts}\times (1+\text{Driver Efficiency Loss})$

Why is understanding system watts important?

• • Knowing the system watts helps in accurately forecasting energy consumption and costs, ensuring you select the most energy-efficient and cost-effective lighting solutions.